Treadmills have become popular in recent years for both home and office use to enable exercisers to run indoors in small confines. Most exercise treadmills include first and second roller assemblies that are rotatably mounted across opposite ends of a frame. An endless belt is trained about the roller assemblies. The upper run of the belt is supported by a slider deck disposed between the frame and the upper run of the belt. In order to cushion the impact of an exerciser's feet on the treadmill belt, the slider deck on many conventional treadmills is mounted on the frame using a shock absorbing mechanism.
One method of mounting a treadmill deck to reduce impact on an exerciser's feet, ankles and legs is disclosed by U.S. Pat. No. 4,974,831 to Dunham. The treadmill disclosed therein has a deck that is pivotally mounted at one end to the frame, with the other end of the deck being supported by a suspension system utilizing lever arms. Each lever arm is pivotally connected at one end to the deck, and at the lever arm's midpoint to the frame. Shock absorbers are interconnected between the opposite end of each lever arm and the frame. Striding on the deck results in pivoting of the lever arms and extension of the shock absorbers to dampen the impact of the exerciser's feet. While this shock absorption system is very successful, it is complex and therefore costly to manufacture.
Other conventional treadmills have utilized rubber blocks placed between the deck and the frame to absorb impact. One such conventional treadmill is disclosed in French Patent No. 2,616,132. A treadmill deck is mounted above treadmill frame members on a plurality of flexible pads. Bushings are inserted into the top and bottom of each pad, and bolts depending downwardly from the deck and upwardly from the frame are received within corresponding bushings. The bolts serve to position the flexible pads between the deck and the frame for shock absorption.
While the treadmill disclosed by French Patent No. 2,616,132 is less complex than the above-described lever and shock absorber mechanical suspension system, it does not perform equivalently for exercisers of differing weights. Flexible pads that are sufficiently small to deform under the impact of an exerciser of low weight would be insufficient to absorb the impact resulting from exercise by a larger person. Similarly, if flexible pads of sufficient size and stiffness are used to adequately cushion and protect a larger exerciser, the flexible pads would not compress sufficiently under the weight of a smaller exerciser and therefore would provide insufficient shock absorption for such smaller exercisers.
An additional drawback of the treadmill disclosed by French Patent No. 2,616,132 is that the flexible pads, as mounted between opposing studs, are capable of deforming in a manner that would allow the treadmill deck to move forward and aft or side-to-side relative to the treadmill frame during impact. To partially overcome this drawback, the French patent includes a flexible stopper secured to a bracket depending downwardly from the underside of the deck that bears against a member of the frame. While this construction would serve to limit forward movement of the deck relative to the frame, no provision is provided for preventing undesirable side-to-side motion of the deck relative to the frame. Additionally, inclusion of the two opposing bolts to mount each flexible pad and the need to include a separate stop assembly raises the complexity of assembly and cost of the treadmill.